Butylbenzothiazole Sulfenamide
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HS Code |
166765 |
| Chemical Formula | C11H14N2S2 |
| Molecular Weight | 238.37 g/mol |
| Appearance | Light - colored powder |
| Odor | Slight characteristic odor |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in some organic solvents like benzene, toluene |
| Melting Point | 102 - 108 °C |
| Flash Point | Approx. 177 °C |
| Density | 1.26 - 1.32 g/cm³ |
| Stability | Stable under normal conditions |
| Toxicity | Moderately toxic, may cause skin and eye irritation |
As an accredited Butylbenzothiazole Sulfenamide factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Butylbenzothiazole Sulfenamide: 25 - kg bags for chemical packaging. |
| Shipping | Butylbenzothiazole Sulfenamide is shipped in sealed, corrosion - resistant containers. Compliance with chemical transport regulations is ensured. Care is taken to prevent exposure during transit, with proper labeling for hazard awareness. |
| Storage | Butylbenzothiazole Sulfenamide should be stored in a cool, dry, well - ventilated area. Keep it away from heat sources, open flames, and oxidizing agents. Store in tightly - sealed containers to prevent moisture absorption and contamination. This helps maintain its chemical stability and reduces the risk of degradation or hazardous reactions. |
Passenger Car Radial Tire Tread Compounds: Scorch Safety Margins and Dynamic Modulus OptimizationMixing of solution-polymerized SBR with high-styrene content (21–25% bound styrene) and high-cis butadiene rubber in a 75:25 blend ratio is executed in an intermeshing twin-screw mixer (Farrel Pomini, 270 L chamber volume, 30–40 rpm rotor speed). N-butylbenzothiazole sulfenamide is dosed at 1.1 phr together with 0.2 phr of a diphenylguanidine-type secondary accelerator to tune the scorch delay to 8.5–10.2 min at 135 °C as per ASTM D5289-21 (MDR 2000, 0.5° arc). The masterbatch is discharged at 155–162 °C, sheeted on a two-roll mill, and cooled; a second non-productive pass incorporates 1.5 phr sulfur and silane coupling agent (4.0 phr TESPT) to anchor silica dispersion. Tread extrusion proceeds through a pin-barrel cold-feed extruder (L/D 16:1, screw diameter 120 mm) with a breaker plate pressure of 18–22 MPa, maintaining a profile tolerance of ±0.15 mm. Cure is conducted in a segmented press at 165 °C for a time corresponding to t90 + 3 min, verified by on-line rheometer sampling. Industry compliance references include FMVSS 139 (endurance and high-speed performance) and ECE R30 for passenger car tires, while compound properties must align with ASTM D3191 (SBR-based standard formulation) and SAE J1554 for heat-build-up limits. Finished articles are P-metric radial tires in speed ratings H through W, covering wet-grip indices above 1.25 (label class B) and rolling resistance values below 7.5 kg/t. Managing Reversion Resistance in Long-Haul TBR Tread: The Role of Sulfenamide Accelerator SelectionNatural rubber (80–85 phr) compounded with budadiene rubber and high-surface-area carbon black (N115, 50 phr) relies on N-butylbenzothiazole sulfenamide at an addition level of 1.3 phr to extend the reversion-free plateau. The vulcanization kinetics, monitored by moving-die rheometry at 160 °C, yield a delta torque (MH-ML) of 18.2 ± 0.4 dN·m and a retention of 94% of MH after 30 minutes—a critical parameter for tires with shoulder temperatures exceeding 95 °C under full-load continuous operation. To suppress anaerobic aging of the polymer backbone, 0.3 phr of hexamethylene-1,6-bis(thiosulfate) disodium salt is used in conjunction; the resulting compound passes the ASTM D623 Method A Goodrich flexometer test with a blowout time exceeding 65 min at 100 °C. A four-extruder line producing quad-plex tread combines cap, base, wing, and cushion gum layers; each stream is temperature-controlled independently through closed-loop oil circuits maintaining head temperatures of 105–115 °C. Press curing in 63-inch dual-cavity presses relies on a segmented bladder pressure profile ramping from 1.2 MPa to 2.1 MPa. Regulatory conformity demands DOT 119 marking, and adherence to the rolling resistance limits of EU 2020/740 is mandatory for C3 tires sold in the EU. End-use applications include drive-axle tires for Class 8 heavy trucks and steer-position tires with tread depths of 22/32-inch. Production of a DIN-X impact-resistant conveyor belt cover compound commences with an upside-down mixing sequence in a 320 L intermeshing mixer: natural rubber mastication with peptizer, followed by N330 carbon black and 1.2 phr N-butylbenzothiazole sulfenamide added at the 80 °C mark to ensure homogeneous dispersion before the scorch threshold is reached. The addition ratio is reduced to 0.9 phr for the carcass skim compound, where sulfur migration to the steel cord interface must be minimized to preserve adhesion. The compound is dumped at 145 °C and immediately passed through a strainer extruder equipped with a 40-mesh screen to remove hard carbon agglomerates. Calendering onto polyester/nylon fabric is performed on a 4-roll Z-configuration calender with roll temperatures of 65–75 °C; the resultant coated ply exhibits a peel adhesion of ≥12 N/mm per ISO 252:2023. Continuous drum vulcanization at 170 °C under pressure of 6 bar yields a cover surface resistivity of ≤3×10⁸ Ω to meet EN ISO 284 electrostatic requirements. Full-belt testing against ISO 14890:2013 and DIN 22102 verifies tensile strength (≥25 MPa) and elongation at break (≥400%). Typical finished products include abrasion-resistant belts for lignite handling with a top cover thickness of 10 mm and heat-resistant belts for clinker transport rated for continuous material temperatures up to 150 °C. How does N-butylbenzothiazole sulfenamide affect compression set in EPDM-based weatherseals?EPDM sponge and dense profiles for automotive weatherseals are formulated with high loadings of carbon black N550 (120 phr) and precipitated calcium carbonate (80 phr), where plasticizer migration into the matrix would otherwise reduce crosslink density. N-butylbenzothiazole sulfenamide at 0.7 phr synergizes with zinc dibutyldithiocarbamate (0.8 phr) to produce a plateau cure that achieves a reversion resistance of ≤3% torque decay after 20 min at 180 °C in an MDR. The compound is extruded through a 90 mm vented single-screw extruder with a profile die; dimensional stability is maintained by a Haake torque rheometer feedback loop that adjusts screw speed within 12–18 rpm. Continuous vulcanization occurs in a microwave-hot-air tunnel (UHF 6.4 kW microwave followed by 12 m hot-air chamber at 230 °C), achieving a cure state equivalent to t95 at a line speed of 22 m/min. Compression set after 22 h at 70 °C is measured at <15% per ASTM D1056-20 Type 2, Class D, meeting the OEM specifications for door body seals with a service life target of 15 years. Regulatory compliance extends to REACH (SVHC-free declaration) and GMP 21 CFR 177.2600 for incidental food contact in cold-room door gaskets. Finished outputs span primary door weatherstrips, glass run channels, and trunk lid seals for A-, B-, and C-segment vehicles. Hydraulic Hose Inner Liner and Cover: Balanced SBR/NBR Vulcanization KineticsIn spiral-wire reinforced hydraulic hoses conforming to SAE J517 100R12, the inner tube is extruded from an NBR compound with 34% acrylonitrile content, plasticized with mesamoll (15 phr), and accelerated using 1.0 phr N-butylbenzothiazole sulfenamide combined with 0.5 phr tetramethylthiuram monosulfide to balance scorch safety and fast cure during lead-press vulcanization. The cover compound, based on CR or a CSM blend for high-temperature resistance, employs 0.8 phr of the same sulfenamide with an in-situ peroxide co-agent system to achieve interlayer adhesion without textile reinforcement. Extrusion is carried out on a duplex cross-head die with laser micrometer diameter control (tolerance ±0.1 mm) before assembly onto a rigid mandrel. The wrapped hose is placed in a lead-sheath press and cured in an autoclave at 155 °C for 45 min under 18 bar nitrogen pressure. Burst pressure testing at 4× working pressure, impulse endurance to 400,000 cycles at 100 °C, and volumetric expansion below 2.0 cm³/m are verified against EN 853 2SN specifications. These hoses serve as critical fluid transfer lines in excavator booms, crane hydraulics, and underground mining shearers, operating at nominal pressures up to 420 bar. Engine mount compounds based on natural rubber and bromobutyl blends demand extreme fatigue resistance and high-energy absorption. N-butylbenzothiazole sulfenamide at 1.3 phr provides a processing window of ±3 °C in the rheometer cure curve, critical for injection molding with a hot-runner mold at 185 °C. Scorch safety, measured as ts2 at 135 °C per ASTM D5289, exceeds 12 min, allowing the compound to fill multi-cavity tools through gates as small as 1.5 mm without premature vulcanization. The molding cycle on a 500-ton horizontal injection press with a platen size of 1,200 × 1,200 mm is set to 5 min at 180–190 °C; demolding forces are reduced by application of a semi-permanent PTFE release coating that is replenished every 2,000 shots. Dynamic characterization according to ISO 10846-1 (dynamic stiffness and damping) reports a loss factor of ≥0.15 at 1 Hz and 22 °C. Verification of material performance relies on the ISO 9001:2015-aligned production part approval process (PPAP Level 3) required by tier-one automotive suppliers. The molded components are integrated into hydraulic engine mounts with integrated travel limiters, designed to withstand 1×10⁶ loading cycles in the 0–3 kN range without delamination or spring rate drift beyond 5%. Ancillary applications include transmission strut mounts and torque rods. The corresponding compliance framework embraces FMVSS 302 for flammability, RoHS II (Directive 2011/65/EU) for substance restrictions, and material specification GMW3055 for elastomeric body mounts.
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Butylbenzothiazole Sulfenamide designates the compound N‑tert‑butyl‑2‑benzothiazolesulfenamide (CAS 95‑31‑8), a delayed‑action primary accelerator supplied commercially as a faintly yellow to off‑white granular powder, oil‑treated powder for low‑dust handling, or pastille form. A representative release specification includes assay (HPLC, internal method) ≥ 97.0 %, free amine (as tert‑butylamine) ≤ 0.50 %, ash ≤ 0.30 %, moisture (Karl Fischer) ≤ 0.50 %, and melting point (capillary) ≥ 104 °C with a typical range of 105–112 °C. The accelerator is used predominantly in the sulfur vulcanization of diene elastomers—natural rubber, styrene‑butadiene rubber, and polybutadiene—in applications demanding a controlled induction period and high crosslink density, such as passenger‑car tire treads, conveyor belts, and extruded sealing profiles. Unlike the parent mercaptobenzothiazole disulfide (MBTS) and the faster sulfenamide CBS, TBBS provides an intermediate scorch safety window coupled with efficient cure rate, allowing compound flow during injection molding while developing a mono‑ to disulfidic crosslink network with good oxidative aging resistance.
The accelerator decomposes thermally during the scorch phase to liberate mercaptobenzothiazole (MBT) and a tert‑butylamine residue. Activation energy for the rate‑limiting step, determined from moving‑die rheometer (MDR) cure curves at multiple temperatures in line with ISO 6502‑3, falls in the range 85–95 kJ/mol for a model NR/BR 70/30 tread formulation with 0.6 phr TBBS and 2.5 phr sulfur. Under a standard MDR protocol (150 °C, 1° arc, die gap 0.5 mm), the scorch time ts2 (time to a 2‑dNm rise above minimum torque) is typically 4.8–5.5 min. The subsequent cure rate index (CR = 100/(t90 − ts2)) reaches 22–28 min⁻¹, enabling a t90 of 8.5–10 min. The vulcanization pathway favors monosulfidic crosslinks when the sulfur‑to‑accelerator ratio drops below 2.5, which raises the crosslink density (ve, measured by swelling in toluene per ASTM D6814) to 1.8–2.2 × 10⁻⁴ mol/cm³ and shifts the loss tangent (tan δ at 60 °C, DMA 10 Hz) downward by 15–20 % compared with CBS‑cured analogs, a property exploited for low‑rolling‑resistance tire compounds.
In a compound containing 0.7 phr accelerator and 2.2 phr sulfur with carbon black N330 at 50 phr, TBBS delivers a measurably longer flow window. At 140 °C MDR, ts2 for the CBS variant reaches 3.2–3.8 min; for TBBS, the value extends to 5.0–5.8 min. This difference assumes practical significance in injection‑molded goods where sprue‑to‑cavity distances exceed 300 mm and melt residence‑time is prolonged. At the same loading, TBBS generates a 6–8 % higher maximum torque (MH), indicating superior crosslinking efficiency. Furthermore, CBS decomposes to cyclohexylamine, a secondary amine known to form N‑nitrosamines under certain curing conditions; TBBS releases tert‑butylamine, a primary amine whose N‑nitroso derivative is notably unstable, thus aligning with the European Directive 93/11/EEC restrictions on N‑nitrosamines in rubber articles. The comparative MDR data and physical properties are provided in the following table.
| Parameter | TBBS | CBS | MBS (OBS) | DCBS |
|---|---|---|---|---|
| Scorch time ts2 (150 °C, min) | 5.1 | 3.7 | 6.8 | 9.3 |
| Optimum cure t90 (min) | 9.2 | 7.0 | 11.5 | 14.2 |
| Max. torque MH (dNm) | 18.5 | 17.2 | 18.1 | 17.8 |
| Tensile strength (MPa, ASTM D412) | 24.1 | 22.8 | 23.4 | 22.9 |
| Elongation at break (%) | 540 | 560 | 570 | 585 |
| Heat aging (7 d 100 °C), retention TS (%) | 78 | 72 | 74 | 76 |
| Formulation: NR/BR 70/30, N330 50 phr, sulfur 2.2 phr, accelerator 0.7 phr, ZnO 3 phr, stearic acid 2 phr. Cure: 150 °C to t90. | ||||
MBS (N‑oxydiethylene‑2‑benzothiazolesulfenamide) provides greater scorch delay but slower cure, whereas DCBS (N,N‑dicyclohexyl‑2‑benzothiazolesulfenamide) offers the longest delay, suited to thick‑section air springs or large‑diameter hose where heat transfer governs cure state. For most general‑purpose mechanical goods, TBBS occupies the optimal balance between flow safety and throughput, particularly when cure temperatures exceed 160 °C where CBS scorch time collapses below 2 min and becomes impractical.
Compounding TBBS at 1.2 phr with sulfur content reduced to 1.8 phr (ratio 1.5) shifts the network structure toward predominantly monosulfidic bonds (av. sulfur rank 1.2–1.5, determined by thiol‑amine probe analysis). While this configuration delivers superior heat‑aging resistance—retention of tensile strength after 14 days at 100 °C per ISO 188 exceeds 85 %—the reversion resistance at temperatures above 160 °C becomes critically sensitive to dwell. When MDR cure time at 170 °C is extended by 20 % beyond t90, torque decline (reversion) exceeds 12 % for the low‑sulfur system, against 6 % for a conventional sulfur‑rich (2.5 phr) recipe. This behavior demands precise cure‑cycle timing on multi‑cavity injection presses with hot‑runner temperatures varying ±3 °C. Additionally, addition of a secondary ultra‑accelerator such as TMTD at 0.05 phr collapses ts2 to below 2.5 min at 140 °C, rendering the compound unmoldable on multi‑core mandrel tools. Therefore, where sulfur‑to‑accelerator ratio falls below 2.0, the compounder must strictly avoid amine‑based co‑accelerators and must enforce a maximum compound storage time of 4 h at ambient shop‑floor temperatures above 30 °C to prevent premature crosslinking during staging.
Production‑scale handling of oil‑coated TBBS powders in a tangential 270 L Banbury mixer with intermeshing rotors requires a two‑stage mixing cycle to decouple filler dispersion from curative addition. In the first stage, raw polymer, carbon black, zinc oxide, and stearic acid are masticated and discharged at 155–165 °C after 3.5–4.0 min ram‑up time. The masterbatch must be cooled on an open mill or in a dump extruder to below 60 °C before stage‑two mixing, where TBBS and sulfur are incorporated at an initial mixer wall temperature of 30 °C and a rotor speed of 25 rpm. Discharge temperature must not exceed 115 °C; excursions to 122–125 °C have been observed to cause local scorch nucleated at metal surfaces, manifesting as gel particles 0.5–1.0 mm in diameter visible in thin‑sheet press cures. Silica‑based compounds impose additional heat accumulation because silanization reactions raise batch temperature during the coupling phase; here, a three‑stage internal mixing protocol with an intermediate rest of 4–8 h at ≤ 35 °C is recommended. On a twin‑screw extruder (L/D 32:1) operating at 200 rpm for continuous compounding, TBBS is preferably metered downstream into the high‑shear zone via a side feeder to limit residence time to 15–25 s above 110 °C and ensure a strand‑pelletized compound with Mooney viscosity (ML 1+4 100 °C, ASTM D1646) within ±3 MU of the target value.| Property | Specification | Test Method |
|---|---|---|
| Assay (as TBBS) | ≥ 97.0 % | HPLC (in‑house) |
| Melting point | ≥ 104 °C (range 105–112 °C) | Capillary, ASTM D1519 equivalent |
| Ash content | ≤ 0.30 % | ISO 247‑1 |
| Volatile matter | ≤ 0.50 % | Karl Fischer (moisture) / oven loss |
| Free amine | ≤ 0.50 % | Acid‑base titration |
| Residue on 100 mesh screen | ≤ 0.10 % | Wet sieving |
| Oil content (if oil‑treated) | 1.0–2.0 % | Extraction |
